Bioretention: Also
known as Rain Garden, Bio-Filter and an LID BMP. On-lot
retention of stormwater through the use of vegetated
depressions engineered to collect, store, and infiltrate
runoff.
BMP: Best Management Practice; a practice or
combination of practices that are the most effective and
practicable (including technological, economic, and
institutional considerations) means of controlling point or
nonpoint source pollutants at levels compatible with
environmental quality goals.
Buffer: A vegetated zone adjacent to a stream,
wetland, or shoreline where development is restricted or
controlled to minimize the effects of development.
Cluster Development: Buildings concentrated in
specific areas to minimize infrastructure and development
costs while achieving the allowable density. This approach
allows the preservation of natural open space for
recreation, common open space, and preservation of
environmentally sensitive features.
Curbs: Concrete barriers on the edges of streets used
to direct stormwater runoff to an inlet or storm drain and
to protect lawns and sidewalks from vehicles.
Design storm: A rainfall event of specific size,
intensity, and return frequency (e.g.,. the 1-year storm)
that is used to calculate runoff volume and peak discharge
rate.
Detention: The temporary storage of stormwater to
control discharge rates, allow for infiltration, and improve
water quality.
Dissolved Oxygen (DO):
Amount of oxygen dissolved in water. The DO is expressed in
parts per million (ppm) or milligrams per liter (mg/L).
Dry Well: Small excavated trenches filled with stone
to control and infiltrate rooftop runoff. EPA: Environmental
Protection Agency. Erosion: The process of soil detachment
and movement by the forces of water.
Fecal Coliform:
Bacteria found only in the intestinal tracts of humans and
animals. The major sources are animal waste, waste treatment
plants, and failing septic systems. The presence of this
bacteria typically indicates pollution that may pose a
potential health risk.
Filter Strips: Bands of closely-growing vegetation,
usually grass, planted between pollution sources and
downstream receiving waterbodies.
Geographic Information System (GIS): A system for
capturing, storing, checking, integrating, manipulating,
analyzing and displaying geographically referenced data.
Greenway: A linear open space; a corridor composed of
natural vegetation. Greenways can be used to create
connected networks of open space that include traditional
parks and natural areas.
Groundwater: Water stored underground in the pore
spaces between soil particles or rock fractures.
Habitat: An area or type of area that supports plant
or animal life.
Hydrology: The science dealing with the waters of the
earth, their distribution on the surface and underground,
and the cycle involving evaporation, precipitation, flow to
the seas, etc.
Hypothesis: A
statement that predicts what you think will happen.
IMP: Intregrated management practice. A LID practice
or combination of practices that are the most effective and
practicable (including technological, economic, and
institutional considerations) means of controlling the
predevelopment site hydrology.
Impervious Area: A hard surface area (e.g., parking
lot or rooftop) that prevents or retards the entry of water
into the soil, thus causing water to run off the surface in
greater quantities and at an increased rate of flow.
Imperviousness Overlay Zoning: One form of the
overlay zoning process. Environmental aspects of future
imperviousness are estimated based on the future zoning
build-out conditions. Estimated impacts are compared with
watershed protection goals to determine the limit for total
impervious surfaces in the watershed. Imperviousness overlay
zoning areas are then used to define subdivision layout
options that conform to the total imperviousness limit.
Incentive Zoning: Zoning that provides for
give-and-take compromise on zoning restrictions, allowing
for more flexibility to provide environmental protection.
Incentive zoning allows a developer to exceed a zoning
ordinances limitations if the developer agrees to fulfill
conditions specified in the ordinance. The developer may be
allowed greater lot yields by a specified amount in exchange
for providing open spaces within the development.
Infiltration: The downward movement of water from the land
surface into the soil.
Level Spreader: An outlet designed to convert
concentrated runoff to sheet flow and disperse it uniformly
across a slope to prevent erosion.
Low Impact Development: The integration of site
ecological and environmental goal and requirements into all
phases of urban planning and design from the individual
residential lot level to the entire watershed.
Macroinvertebrate:
An organism that lacks a backbone and is visible without
magnification. Examples include snails, worms, fly larvae,
and crayfish ("crawdads").
Nonpoint Source Pollution: Water pollution caused by
rainfall or snowmelt moving both over and through the ground
and carrying with it a variety of pollutants associated with
human land uses. A nonpoint source is any source of water
pollution that does not meet the legal definition of point
source in section 502(14) of the Federal Clean Water Act.
NPDES: National Pollutant Discharge Elimination
System; a regulatory program in the Federal Clean Water Act
that prohibits the discharge of pollutants into surface
waters of the United States without a permit.
Open Space: Land set aside for public or private use
within a development that is not built upon.
Overlay Districts: Zoning districts in which
additional regulatory standards are superimposed on existing
zoning. Overlay districts provide a method of placing
special restrictions in addition to those required by basic
zoning ordinances.
Particulates: Small
pieces of material floating in water.
Permeable: Soil or other material that allows the
infiltration or passage of water or other liquids.
pH: Measures the
Hydrogen (H+) ion concentration of a substance. It is based
on a scale that ranges from 0 (most acidic) to 14 (most
basic). A pH of 7 is considered neutral. Each unit of change
represents a tenfold change in acidity or alkalinity.
Planned Unit Development (PUD) Zoning: Planned unit
development provisions allow land to be developed in a
manner that does not conform with existing requirements of
any of the standard zoning districts. The PUD allows greater
flexibility and innovation than conventional standards
because a planned unit is regulated as one unit instead of
each lot being regulated separately.
Rain Barrels: Barrels designed to collect and store
rooftop runoff. Recharge Area: A land area in which surface
water infiltrates the soil and reaches the zone of
saturation or groundwater table.
Rain Garden: See
bioretention. Synonymous with bioretention, this term
is typically used for general audience
discussions.
Riparian Area: Vegetated ecosystems along a waterbody
through which energy, materials, and water pass. Riparian
areas characteristically have a high water table and are
subject to periodic flooding.
Runoff: Water from rain, melted snow, or irrigation
that flows over the land surface.
Scientific Method: A systematic approach involving
recognition of a problem, formulation of a hypothesis,
development of an experiment, observation and analysis of
the results, and a conclusion that may reject or accept the
hypothesis. More...
SCS: U.S. Department of Agriculture Soil Conservation
Service; renamed the Natural Resources Conservation Service
(NRCS).
Sediment Control Device: A protection device used to
cover a drainage inlet during the course of construction to
prevent sediment and debris from entering the drainage
system.
Site Fingerprinting: Development approach that places
development away from environmentally sensitive areas
(wetlands, steep slopes, etc.), future open spaces, tree
save areas, future restoration areas, and temporary and
permanent vegetative forest buffer zones. Ground disturbance
is confined to areas where structures, roads, and
rights-of-way will exist after construction is complete.
Subdivision: The process of dividing parcels of land
into smaller building units, roads, open spaces, and
utilities.
Swale: An open drainage channel designed to detain or
infiltrate stormwater runoff.
Turbidity: Measures
the clarity of water. High turbidity results when there are
a lot of particulates floating around and the water is
cloudy. Low turbidity results when there are few floating
particulates and the water is clear.
Underdrain: A
perforated pipe, typically 4-6" in diameter placed
longitudinally at the invert of a bioretention facility for
the purposes of achieving a desired discharge rate.
Urbanization: Changing land use from rural
characteristics to urban (city-like) characteristics.
Urban Sprawl: Development patterns, where rural land
is converted to urban uses more quickly than needed to house
new residents and support new businesses. As a result people
become more dependent on automobiles and have to commute
farther. Sprawl defines patterns of urban growth that
include large acreage of low-density residential
development, rigid separation between residential and
commercial uses, residential and commercial development in
rural areas away from urban centers, minimal support for
nonmotorized transportation methods, and a lack of
integrated transportation and land use planning.
USGS: United States Geological Survey, an agency
within the Department of the Interior.
Watershed: The topographic boundary within which
water drains into a particular river, stream, wetland, or
body of water.
Watershed-based Zoning: Zoning that achieves
watershed protection goals by creating a watershed
development plan, using zoning as the basis (flexible
density and subdivision layout specifications), that falls
within the range of density and imperviousness allowable for
the watershed to prevent environmental impacts.
Watershed-based zoning usually employs a mixture of zoning
practices.
Wet pond: A stormwater management pond designed to
detain urban runoff and always contain water. Zero-lot-line
Development: A development option in which side yard
restrictions are reduced and the building abuts a side lot
line. Overall unit-lot densities are therefore increased.
Zero-lot-line development can result in increased protection
of natural resources, as well as reduction in requirements
for road and sidewalk.
Zoning: Establishes minimum criteria to be used when
assessing whether a particular project is appropriate for a
certain area; ensures that the end result adheres to an
acceptable level of performance or compatibility. Regulations or requirements that govern the
use, placement, spacing, and size of land and buildings
within a specific area.
